JEE Main On 16 April 2018 Question 8
Question: A thin circular disk is in the $ xy $ plane as shown in the figure. The ratio of its moment of inertia about z and z? axes will be [JEE Main 16-4-2018]
Options:
A) $ 1:2 $
B) $ 1:4 $
C) $ 1:3 $
D) $ 1:5 $
Show Answer
Answer:
Correct Answer: C
Solution:
We know that, the moment of inertia of the circular disk about the center is
$ M _{Z}=\frac{MR^{2}}{2} $
Using parallel axis theorem,
$ M_Z^{’}=\frac{MR^{2}}{2}+MR^{2}=\frac{3MR^{2}}{2} $
$ \frac{M _{Z}}{M_Z^{’}}=1/3 $
